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991.
992.
Differential role of microenvironment in microencapsulation for improved cell tolerance to stress 总被引:6,自引:0,他引:6
Sun ZJ Lv GJ Li SY Yu WT Wang W Xie YB Ma X 《Applied microbiology and biotechnology》2007,75(6):1419-1427
The effect of the microenvironment in alginate–chitosan–alginate (ACA) microcapsules with liquid core (LCM) and solid core
(SCM) on the physiology and stress tolerance of Sacchromyces cerevisiae was studied. The suspended cells were used as control. Cells cultured in liquid core microcapsules showed a nearly twofold
increase in the intracellular glycerol content, trehalose content, and the superoxide dismutase (SOD) activity, which are
stress tolerance substances, while SCM did not cause the significant physiological variation. In accordance with the physiological
modification after being challenged with osmotic stress (NaCl), oxidative stress (H2O2), ethanol stress, and heat shock stress, the cell survival in LCM was increased. However, SCM can only protect the cells
from damaging under ethanol stress. Cells released from LCM were more resistant to hyperosmotic stress, oxidative stress,
and heat shock stress than cells liberated from SCM. Based on reasonable analysis, a method was established to estimate the
effect of microenvironment of LCM and SCM on the protection of cells against stress factors. It was found that the resistance
of LCM to hyperosmotic stress, oxidative stress, and heat shock stress mainly depend on the domestication effect of LCM’s
microenvironment. The physical barrier of LCM constituted by alginate–chitosan membrane and liquid alginate matrix separated
the cells from the damage of oxidative stress and ethanol stress. The significant tolerance against ethanol stress of SCM
attributed to the physical barrier consists of solid alginate–calcium matrix and alginate–chitosan membrane. 相似文献
993.
The biological effects of rare-earth ions on the organism have been studied using Pr3+ as a probe ion and Escherichia coli cell as a target. Atomic force microscopy (AFM) observation of the surface of E. coli cells shows that the presence of Pr3+ substantially changes the structure of the outer membrane. By induced coupled plasma-mass spectrometry (ICP-MS), more Cu2+ was found in the cells grown in the presence of Pr3+, indicating changes of cell permeability. Using energy dispersive X-ray spectroscopy (EDX), Ca2+ is found on the outer surface of the original cell. It is proposed that Pr3+ can replace Ca2+ from the binding sites because of their close ionic radii and similar ligand speciality. 相似文献
994.
Trapa maximowiczii is a floating-leaved macrophyte common in China. The plant population in East Bay, Lake Taihu, has been expanding rapidly
in recent years. In order to better understand the mechanisms controlling the population dynamics in this species, two outdoor
experiments were conducted from 9 May to 8 July 2007, evaluating the effect on the growth of T. maximowiczii of different nutrient levels in water column and sediment. Results showed that high concentration of nutrients (nitrogen
and phosphorous) in water led to significant increases in rosette diameter and plant dry weight, dry weight of aquatic roots
and anchoring roots, but had no effect on plant height or main stem node count. Phosphorus enrichment resulted in increases
in plant dry weight and seed number. However, no such difference was observed between the nitrogen enrichment treatment and
the control. Sediment fertility had significant effects on plant growth. Plant height, plant dry weight, dry weight of aquatic
and anchoring roots, and maximum rosette diameter were significantly greater in high-nutrient sediment than those in low-nutrient
sediment. This study suggests that eutrophication of water (especially increasing phosphorus loading) and accumulated nutrients
in sediment may be among the causes leading to increasing biomass of the floating-leaved macrophyte T. maximowiczii in East Bay of Lake Taihu. 相似文献
995.
Isolation of diallyl trisulfide inducible differentially expressed genes in human gastric cancer cells by modified cDNA representational difference analysis 总被引:17,自引:0,他引:17
Extensive epidemiologic studies indicated protective effects of consumption of garlic on reducing human gastric cancer (HGC) incidence. Diallyl trisulfide (DATS), a critical organic allyl sulfur component of garlic, was reported to have chemopreventive effects in inhibiting tumor process. We used DATS to treat HGC cell line BGC823 cells, and showed that DATS induces G1/S arrest and apoptosis in BGC823 cells demonstrated by a flow cytometric analysis. To further isolate DATS inducible differentially expressed genes in BGC823 cells, we combined a highly specific subtractive hybridization of cDNA representational difference analysis (cDNA RDA) with a sensitive bidirectional radioactive detection of mRNA differential display (mRNA DD) to develop a subtractive hybridization differential display (SHDD) method. This modified method adopted a first round of bidirectional subtractive hybridization between two sample cDNAs and a second round of bidirectional subtractive hybridization between the two resultant first-round difference products. Bidirectional subtractive hybridizations magnified the differences between the two sample cDNAs and favored isolating mRNA species with very small expression differences. We employed the SHDD method to detect DATS inducible differentially expressed genes in BGC823 cells. A total of 14 cDNA fragments (11 upregulated and 3 downregulated by DATS treatment) were isolated and confirmed by reverse Northern blot analysis. Our data show that SHDD is a powerful technique for identifying differentially expressed mRNA species between two sample cDNAs and provide useful cellular and molecular information for understanding the effects of garlic against human gastric cancer. 相似文献
996.
低氧提高肿瘤细胞反义VEGF165基因表达 总被引:3,自引:0,他引:3
为了探讨反义VEGF1 65基因对食管癌的抑制作用 ,并初步探讨利用肿瘤低氧微环境改善基因治疗的效果 ,采用PCR技术和DNA重组技术构建了含低氧反应元件的真核表达载体 ,并用此载体构建了含荧光素酶报告基因和反义VEGF1 65基因的重组载体。用脂质体将重组载体导入食管癌细胞 ,体外用化学发光光度计测定低氧对报告基因表达的调节和ELISA法间接测定低氧对反义VEGF基因表达的调节作用。体内利用裸鼠皮下移植实验研究低氧对反义VEGF1 65基因抑瘤作用的影响。体外实验表明 ,用带低氧反应元件的重组真核表达载体转染食管癌细胞 ,在低氧培养下可以使报告基因的表达提高 3 780 % ,并可以显著提高反义VEGF1 65基因的表达 ,体内用带低氧反应元件的载体将反义VEGF1 65基因导入食管癌细胞中 ,其抑瘤效果显著优于不含该元件的载体 ,抑瘤率分别为 71 .7%和 5 6 .1 %。反义VEGF1 65基因能显著抑制食管癌的生长 ;利用肿瘤低氧可以实现治疗基因的自主调节 ,改善基因治疗的效果 相似文献
997.
Discovering disease-genes by topological features in human protein-protein interaction network 总被引:3,自引:0,他引:3
MOTIVATION: Mining the hereditary disease-genes from human genome is one of the most important tasks in bioinformatics research. A variety of sequence features and functional similarities between known human hereditary disease-genes and those not known to be involved in disease have been systematically examined and efficient classifiers have been constructed based on the identified common patterns. The availability of human genome-wide protein-protein interactions (PPIs) provides us with new opportunity for discovering hereditary disease-genes by topological features in PPIs network. RESULTS: This analysis reveals that the hereditary disease-genes ascertained from OMIM in the literature-curated (LC) PPIs network are characterized by a larger degree, tendency to interact with other disease-genes, more common neighbors and quick communication to each other whereas those properties could not be detected from the network identified from high-throughput yeast two-hybrid mapping approach (EXP) and predicted interactions (PDT) PPIs network. KNN classifier based on those features was created and on average gained overall prediction accuracy of 0.76 in cross-validation test. Then the classifier was applied to 5262 genes on human genome and predicted 178 novel disease-genes. Some of the predictions have been validated by biological experiments. 相似文献
998.
Alkaline phosphatase(AKP),from the succus entericus of silkworm,was purified using 10%-50% ammonium sulfate fractions,ion exchange chromatography Of DEAE-Sepharose,and size exclusion chromatography of Sephacryl S-200.The purification fold was 464 times and specified activity was 3936 U/mg.Optimum pH value of the phosphatase was 10.5,and was stable between pH 7.5 and 11.The optimum temperature of the phosphatase was 40℃ and it was unstable over 50℃.Km value of the phosphatase was 1.25 mmol/L.In a given condition,the phosphatase was selectively modified by PCMB,NBS,PMSE TNBS,SUAN,DTT,BrAc,and IAc,the results indicate that PMSF,SUA,BrAc,IAc,and TNBS could Obviously inhibit the activity of the phosphatase,and the degree of inhibition depended on the concentration of these reagents.There was little effect on the activity of phosphatase after treatment by PMSF,DTT,and NBT.We primarily conclude that mercapto and imidazole are essential for AKP from silkworm.Also,Lys residue and disulfide bands are necessary to protect the catalysis of the AKP. 相似文献
999.
目的:观察新生SD大鼠原代培养皮层神经元的钙激活钾通道(Kca)在黎芦碱致神经元损伤模型上的激活、抑制效应.方法:采用细胞贴附和内面向外两种膜片钳单通道记录方法记录新生SD大鼠原代培养皮层神经元的Kca电生理活动.结果:黎芦碱在胞外可激活Kca.在有钙浴液内,细胞贴附式,钳制膜电位 30 mV,加入不同浓度黎芦碱(μmol/L:15、25、50、75),通道开放概率由0.005分别增加为0.014±0.003、0.085±0.010、0.132±0.016、0.059±0.006(P<0.01),在50μmol/L以内表现出浓度依赖性.无钙浴液内,细胞贴附式膜片上,钳制膜电位 50 mV,随药物浓度(μmol/L)增加为15、40、60、100时,通道开放概率由0.005分别增加为0.014±0.010、0.113±0.006、0.141±0.004、0 295±0.009(P<0.05).6例内面向外式膜片上,钳制膜电位 40 mV,分别加入黎芦碱25 μmol/L、50μmol/L 3 min后,通道开放概率由0.011±0.008分别增加为0.010±0.010、0.012±0.007(P>0.05).黎芦碱在胞内Kca开放概率,平均开放/关闭时间,电流幅值均无明显变化.结论:黎芦碱通过影响胞内游离钙水平间接调节Kca,在缺血缺氧早期,胞内游离钙增高激活Kca开放. 相似文献
1000.
Li Y Yu WH Ren J Chen W Huang L Kharbanda S Loda M Kufe D 《Molecular cancer research : MCR》2003,1(10):765-775
The DF3/MUC1 transmembrane oncoprotein is aberrantly overexpressed in most human breast carcinomas and interacts with the Wnt effector gamma-catenin. Here, we demonstrate that MUC1 associates constitutively with ErbB2 in human breast cancer cells and that treatment with heregulin/neuregulin-1 (HRG) increases the formation of MUC1-ErbB2 complexes. The importance of the MUC1-ErbB2 interaction is supported by the demonstration that HRG induces binding of MUC1 and gamma-catenin and targeting of the MUC1-gamma-catenin complex to the nucleolus. Significantly, nucleolar localization of gamma-catenin in response to HRG is dependent on MUC1 expression. Moreover, mutation of a RRK motif in the MUC1 cytoplasmic domain abrogates HRG-induced nucleolar localization of MUC1 and gamma-catenin. In concert with these results, we show nucleolar localization of MUC1 and gamma-catenin in human breast carcinomas but not in normal mammary ductal epithelium. These findings demonstrate that MUC1 functions in cross talk between ErbB2 and Wnt pathways by acting as a shuttle for HRG-induced nucleolar targeting of gamma-catenin. 相似文献